Apparatus for facing and truing abrasive articles



April 1-3, 1948.

E. P. DAHLSTROM APPARATUS FOR FACING AND TRUING ABRASIVE ARTICLES FiledAug. 1, 1946 4 Sheets-Sheet 1 Etc? INVENTOR. zaiiz'sirom fliiarnqy April1948- E. P. DAHLSTROM 2, 39,771

APPARATUS FOR FACING AND TRUING ABRASIVE ARTICLES Filed Aug. 1, 1946 4Sheets-Sheet 2 INVENTOR.

Eric 7. 2m Z5 from ornqy April 1948. E. P. DAHLSTROM 2,439,771

APPARATUS FOR FACING AND TRUING ABRASiEVE ARTICLES Filed Aug. 1, 1946 4Sheets-Sheet 3 Jig. 5.

IN VEN TOR.

E1 to 217a?! Z5570? fiifily April 13, 1948. E. P. DAHLSTROM 2,439,771

APPARATUS FOR FACING AND TRUING ABRASIVE ARTICLES Filed Aug. 1, 1946 4Sheets-Sheet 4 Patented Apr. 13, 1948 UNlTED STATES APPARATUS FOR FACINGAND TRUING ABRASIVE ARTICLES Eric P. Dahlstrom, Niagara Falls, N. Y.,assignmto The Carborundum Company, Niagara Falls, N. Y., a corporationof Delaware Application August 1, 1946, Serial No. 687,737

90laims. 1

This invention relates to the manufacture of abrasive articles of therotatable type such as small size arbored grinding and polishing wheelsand cylinders and mounted abrasive bodies of cylindrical shape. It isparticularly concerned with methods and apparatus for truing, facing andedging the working surfaces of such rotatable abrading articles so thatthe grinding or polishing surfaces thereof will be uniform and true withthe finished cylindrical surfaces thereof not only evenly surfaced butaccurately centered in respect to the arbors or spindles of thearticles.

Heretofore truing and edging of rotatable abrasive articles of theaforesaid type have been customarily carried out manually wherein thearticle to be surfaced is rotatably mounted in a suitable chuck orholding device and a. diamond tool. abrasive dressing stick or one ofthe conventional dressing tools such as a Bell dresser, Huntington.dresser, or Ross dresser, manually passed across the rotatingcylindrical surface to be edged and trued. Whenever extreme accuracy hasbeen desired the particular dressing tool has been likewise mounted in aholder for passage across the rotating surface to be edged and trued,Such practices have required the careful and detailed mounting of eachindividual article in its holder and have also required a reasonablyhigh degree of skill in the proper positioning of the dressing tool inorder for the final article to be satisfactorily trued and edged.Obviously, such practices are highly time-consuming and, if carried outby an operator lacking in the requisite skill, are not completelysatisfactory.

It is an object of the present invention to provide an improvedapparatus and method for ed ing and truing rotatable abrading bodiesobviating the above disadvantages. It isa further object to provide animproved apparatus for facing, edging and truing such articles rapidlyand efficiently with a minimum amount of time consumed in carrying outthe operations and with a high degree of accuracy in the truing of theabrading articles.

I have found that rotatable abrading bodies such as arbored grindingwheels and cylinders and mounted abrasive articles of cylindrical shapecan be quickly and accurately faced, edged, and trued in respect to thearbors or spindles thereof by means of a centerless grinding mechanismmodified by the provision of cooperating means for centering theabrading body with respect to the centerless grinding mechanism andpresenting the body to the grinding mechanism. Apparatus in accordancewith the present invention 2 can be so constructed as to perform theedging and truing operation alone or it can be so constructed as tosuccessively face, edge and true the desired article. According to oneembodiment-of my invention, apparatus is provided whereby while onearticle is being faced, a second article, usually previously faced, issimultaneously edged and trued by the same centerless grindingmechanism.

1o Briefly, the apparatus provided in accordance with the presentinvention consists of a centerless grinding mechanism of theconventional type together with coacting mechanism adapted for holding aplurality of articles to be faced and is centered and for presentingthose articles in a succession of stages to the centerless grindingmechanism in such manner that they are first faced on the flat endsurface thereof, when desired, and are then re-positioned and presentedto the centerless grinding mechanism in centered relation thereto sothat the cylindrical surface of the body is edged and trued-with respectto the nounting arbor or spindle of the body being suraced.

In order that the invention may be more clearly understood, reference ismade to the drawings wherein an embodiment of the present inventionadapted for facing, edging and truing rotatable abrading articles inrapid succession is set forth, and wherein Figure 1 is a rearelevational view of an apparatus embodying the principles and featuresof the present invention, and wherein the showing of the centerlessgrinding mechanism is confined to a partial diagrammatic showing of thegrinding wheel and feed wheel thereof;

Figure 2 is a side elevation of'theapparatus shown in Figure 1, showingthe feed wheel of the grinding mechanism partially cut away;

Figure 3 is a vertical view, partially in section, of the apparatusshown in Figures 1 and 2;

Figure 4 is an enlarged view, partly in section, taken on the line 44 ofFigure 2;

Figure 5 is a top plan view taken on the line 5-5 of Figure 2 with theupper center holding means partially cut away;

Figures 6, 7, and 8 are schematic sketches depicting graphically thevarious'positions of the abrading body being treated with respect to thecenterless grinding mechanism, first, as it is mounted in the apparatus,second, as it is moved into position for the end facing operation, andthird, as it is moved into position for the edging and truing operation;

Figure 9 is a rear elevational view of them paratus ofl'igure 1 takenfrom the same position but enlarged in scope to show the completcenterless grinding mechanism, including the adjusting and operatingmeans therefor;

Figure is a side elevation, partially in section, of a modified form ofapparatus consisting of a single rotatable holding member: and

Figure 11 is a rear elevationalview of the mechanism shown in Figure 10,but with the holder angularly displaced to the position which itoccupies when an abrasive body held thereby is in process of beingfaced.

Referring further to the various figures of the drawing, the details ofthe centerless grinding mechanism which constitutes a part of thecomplete operating apparatus of the present invention are not set forthsince the centerless grinding mechanism may be any one of theconventional centerless grinding mechanisms on the market and thedetails thereof are not essential for a complete understanding of thenature of the present invention. Consequently, the showing of thecenterless grinding mechanism is confined to a schematic showing of thegrinding wheel 8, feed wheel Ill and rest or support bar ll thereof,showing the space relationship of those parts of the centerless grindingmechanism to the remainder of the entire apparatus. As therein shown,the axis of the feed wheel Iii is laterally parallel to the axis of thegrinding wheel 9 but adjustably inclined at a. slight downward anglesenting it to the flat side surface of the grinding wheel of thecenterless oration, withdrawing the faced abrasive article and moving itinto an accurately centered position for edging and truing thecylindrical surface of the article and simultaneously receiving andmoving a second abrasive body into position for the facing operation,presenting the first article to the grinding mechanism in centeredrelation for edging and truing of the article while presenting thesecond abrasive body to the grinding wheel to be faced.

Referring again to the various figures of the drawing, the. aforesaidmechanism for holding the articles to be surfaced and'trued andpresenting them to the grinding mechanism in proper positions forsuccessively facing and edging, and also truing, comprises a basestructure i2 upon which is mounted a suitable framework l3 carrying amounting plate l4. The mounting plate It is rotatably supported on ashaft i5 and has mounted therein four holders or chucks [6 which areJournaled in the mounting plate It by means of ball bearing assembliesI! so that each holder or chuckis capable of independent rotation. Asshown, the holders or chucks are radially equidistant from the center ofthe mounting plate I4 and equally spaced one from the other thereon. Itis to be understood that from the horizontal for the purpose of drawingthe article being edged through mechanism, the particular degree ofangle governing the rate of travel of the article being treated throughthe grinding mechanism.

Figure 9 shows further details of the centerless grinding mechanism,including the grinding wheel 9 and regulating wheel i0 which areprovided with suitable truing mechanisms, generally indicated at 50 and5|, for truing the peripheral surfaces of the grinding and regulatingwheels, respectively, when required. Mounted upon the stationary basestructure of the centerless grinding mechanism is a carriage 52supported on surface ways so as to be movable longitudinally of the basestructure; carriage 52 supports the regulating wheel l0 and itsassociated mechanism. A threaded shaft 53 connected to carriage 52, andtogether with hand wheel 54, provides means for moving the carriag 52and regulating wheel in longitudinally along the base of the centerlessgrinding machine to adjust the distance between the regulating andgrinding wheels as desired. The grinding wheel 9 is rotated at a highspeed in clockwise direction, being connected to and the grindingdrivenby a conventional source of power (not shown), and effects a stockremoval from the abrasive body being edged. The regulating wheel II,which rotates at a relatively slow speed, and similarly connected to anddriven by a conventional source of power (not shown in the drawing)controls the rate of rotation of the work'in the machine. in operation,the parallel opposed faces of the wheels travel in opposite directionsand form a grinding throat therebetween through which the abrading bodyto be edged passes. i

The centerless grinding mechanism as shown is modified by the provisionof a holding and positioningmechanism adapted to receive and hold aplurality of rotatable abrasive bodies to be surfaced, accepting andmoving each one in rapid succession in a series of'stages into correctposition for facing the flat end surface thereof, prethe number ofholders or chucks on the mounting plate need not necessarily be four, asshown, but may be any other reasonable number, the partial revolution ofthe mounting plate after each operation obviously depending upon thenumber of holders. The socket area It of each holder is preferablyformed of or lined with an extremely hard, wear-resistant material suchas a bonded tungsten carbide composition, and is of a size to permit aclose fit between it and the mounting spindle of the abrasive article tobe held therein. The mechanism shown in the drawings is depicted asprovided with holding sockets as provided for in thesurfacing and truingof mounted abrading articles 20. When arbored rotatable abradingarticles are being surfaced and trued the holding means, instead ofbeing as shown, are provided with corresponding spindles set in thesockets or in place of the sockets, the spindles being of a size toclosely fit the arbors of the abrasive articles to be surfaced.

Each of the holders or chucks I6 is slidably mounted to permitindependent axial movement to and from the grinding mechanism and arenormally held out of engagement with the grinding mechanism by means ofsprings 2| which are mounted on a shank 22 of each holding meansextending rearwardly from the rear face of the mounting plate i4 andterminating in an enlarged head or button 23 suitable for engagement bythe adjustable extension arms 24 and 25 of an operating lever 26. Theshorter of the two extension arms 24 is adjustable for length byloosening the lock nut 21 thereon and moving the threaded portion 28 ofthe extension arm and again settlngthe lock nut to maintain the desiredposition. This adjustable extension arm 24, upon forward movement of theoperating lever 26, engages the shank 22 of the particular holding meansIt in position for the facing operation, 1. e.,

be faced. The length of the extension arm is determined by the length ofthe abrasive article grinder for the facing op-' being faced and theamount of facing to be performed thereon. The second and longerextension arm 23 of the operating lever 23 at the same time engages theshank 22 of the holding means which isin position for the edging andtruing operation, i. e., the holder in the bottom center position, andimparts an axial movement thereto toward the grinding mechanism. Thisaxial movement is greater than the movement imparted by the adjustableextension arm to, the holder in the left hand position and is sufllcientto carry the abrading body 23 held by the bottom center holding meansinto full engagement by the grinding wheel 3 and feed wheel it of thecenterless grinding mechanism and supported in the proper centeredrelationship to assure accurate centering of the cylindrical surface,when edged, in respect to the spindle or arbor of the article beingedged and trued.

Rotation of the mounting plate through the partial revolution necessaryforbringing each holding means successively into positions for thevarious operational steps, and which is one quarter of a revolution'whenfour holders are employed, is accomplished as follows: As the operatinglever 26 is pulled back and drawn out of holding and pontioningmechanism can be diswith means for vertical adjustment. The rotat ablemounting plate It and associated structureare likewise capable oflateral adjustment for the centering of the holding meansby which itpresents the work to the grinding mechanism to be engagement with theshanks 22 of the holding means It the springs 2| ull the holders it awayfrom the grinding mechanism and the operating lever 23 is forced againstthe trip arm 30 which operates a. valve mechanism 3| which then allowscompressed air to enter a cylinder 32 actuating a piston in thecylinder, which piston is connected to a rack gear 33 which engages anintermediate unidirectional or free gear 34 which in turn is meshed withperipheral gearing 3b of the mounting plate ll, imparting one-quarter ofa revolution to the mounting plate ll. Withdrawal of the operating lever23 from the trip arm 30 cuts off the supply of air to the cylinder 32and conventional spring means provided therein withdraws the pistonwhich, because of the unidirectional action. of the intermediate freegear 34 does not impart any corresponding reversing movement to themounting plate It. The pneumatic action of the air cylinder is dampedorcushioned by means of Hannah speed control valves 36 located in th airline. compressed air is further regulated by means of a conventional airpressure regulator 31. An axially movable stop rod or bar 33 mountedupon the framework I3 and having a tapered gear tooth top face 39adapted for closely meshing with the peripheral gearing of the mountingplate it, and normally held out of engagement therewith by spring til isso positioned that upon forward movement of the operating lever 23 it ismeshed with the peripheral gearing 35 of the mounting plate It so as tomake any minor adjustments necessary to bring the mounting plate It toan exactly 90 turn upon each actuation thereof by the rack gear 33.

It is plainly evident that the pneumatic cylinder mechanism describedherein for actuating the mounting plate can be replaced by a similarlyoperable hydraulic-acting cylinder or by suitable mechanical deviceswithout departing from the spirit and principles of the presentinvention.

The mounting plate It and associated framework I3 is capable of verticaladjustment since the framework i3 is provided with an upwardly extendingcolumn 43 mounted in suitable vertically extending dovetailed slidewaysor gibbs M by which it is vertically adjustable by means of hand wheel35. This vertical adjustment of the trued and edged since it is alsosupported on horizontal dovetail slideways or gibbs 43 which areoperable by means of hand wheel 41.

Operation of the facing, truing and edging apparatus as shown in thevarious figures of the drawing is carried out as follows: Assuming thatthe rotatable mounting plate It and associated structure or frameworkhas been vertically and horizontally adjusted so that the bottomlypositioned holding means is correctly and accurately centered withrespect to the grinding and feed wheels of the centerless grinder sothat an abrading body held by that particular holding means or chuckwill reside in the position shown in Figure 8, the steps are carried-outin the following manner. A mounted cylindrical abrading body to besurfaced, edged and trued is placed in the socket iii of the holdingmeans resting in the top center position (see Figure 6). The operatinglever 23 is then pulled back into engagement with the tri arm 30 whichopens valve 3i letting air into the cylinder 32 which actuates thepiston contained .in the cylinder, thereby rotating the mounting plateIt through, for example, onequarter .of a revolution by means of thegearing means previously described. This partial revolution of themounting plate It brings the holder containing the abrasive body 22inserted therein to the left hand position shown in Figure I. At

this point a second abrading body is inserted in the second holder orchuck which has been brought to the top position on the mounting plateand the operating lever 28 again pushed forward whereupon the holdingmeans in the left hand position shown in Figure 'l is moved forward sothat the abrading body 20 held thereby is presented to the flat face 29of the grinding wheel 9 to be faced thereby. The lever 28 is then pulledThe flow of 1 back to again press against trip arm so and operate valvemechanism 3| whereby the piston in air cylinder 32 is again actuated toimpart another one-quarter revolution to the mounting plate Hi bringingthe third holding means into the upper position (shown in Figure 6)ready for insertion of an article to be surfaced. At the same time, thesecond of the previously inserted abrasive articles is moved to the lefthand position (shown in Figure '7) and the holder carrying the abrasivearticle previously faced is moved into the bottom position (shown inFigure 8) properly centered and positioned for the edging and truingoperation. The operating lever 26 is again pushed forward whereupon thestop bar 38 first engages the gearing 35 of the mounting plate It tomake an minor adjustments necessary for limiting the rotation of themounting plate to exactly so as to accurately center the lower holdingmeans, immediately following which the extension arms 28 and 25 of theoperating lever 26 impart axial movements to the left hand and bottomlypositioned holding means, respectively, to bring the abrasive articleheld by the holder in the left hand position (see Figure "1) into en-'gagement with the fiat face of the grinding wheel for facing, andsimultaneously bringthe faced abrasive article held by the holding meansin the The forward movement of assent:

7. lower position (see Figure 8l-into engagement with the grinding wheelI and feed wheel ll of the grinding mechanism for edging and centering.the holding means in the bottom position is of suiiicient extent to holdthe abrasive article being surfaced accurately centered radially withrespect to the grinding wheel until it has traveled a substantialdistance beyond the forward edge ll of the grinding wheel I, therebyassuring accurate truing of the abrasive article which is then readilyreleased from its holder. The chuck or holder in the right hand positionon the mounting plate is idle. Once the operations have proceeded tothis point it is obvious that upon each forward movement of theoperating lever 28 one abrasive article is being faced while apreviously faced abrasive articie is being edged and trued and upon eachwithdrawal of the operating lever a new abrasive body is inserted in thetop holder for subsequent facing, edging and truing. It is furtherevident that the articles being surfaced are always presented in exactalignment to the grinding'mechanism whereby the end face of the abrasivearticle is accurately surfaced so that the finished face will be at atrue right angle to the axis of the article and the article being edgedand trued also presented in correctly centered relationship to thegrinding mechanism, thereby eliminating any possible error in surfacingof the articles once the apparatus has been correctly adjusted for theparticular'abrasive articles to be surfaced.

Although I have described as my preferred embodiment of the invention anapparatus provided with a plurality of holding means or chucks andadapted for facing as'well as edging and truing rotatable abrasivearticles, a simpler but modified form of the apparatus embodying many ofthe principles and features of the present invention such-as shownvdiagrammatically in Figures 10 and 11 can be utilized wherein, insteadof a plurality of chucks ofholders mounted upon a rotatable mountingplate together with means for rotating the mounting plate to bring therespective holders into operational positions as hereinabove described,such modified apparatus may consist simply of a single rotatable holdingmeans It similar to one of the holders or chucks described above andcapable of vertical and lateral adjustment and provided with anoperating lever or arm 26, said holding means It being capable of axialmovement and mounted in conjunction with a coactlng centerless grindingmechanism so as to rotatably hold and present rotatable abrading bodiesto the grinding mechanism for, facing, edging and truing operations. Inthe case of such a simplified apparatus, the framework l2 supporting therotatable holder is preferably pivotedv at the base at IS so that theholder can'be moved angularly into position for the facing operation asshown in Figure 11 after which it is returned to its vertical positionand the single holding means thereof then moved for. ward axially tobring the faced abrasive body held thereby into centered engagement withthe grinding wheel and feed wheel of the grinding mechanism to edge andtrue the cylindrical surface of the abrasive body.

Such a simplified form of apparatus is incapable of the operationalspeed of production of the apparatus provided with the rotatablemounting plate and multiple holding means, but might be preferred inthose cases wherein relatively small numbers of abrasive bodies are tobe edged and trued and a high degree of accuracy ,nism so that saidabrading body a is desired, but quantity of output is or secondaryimportance.

The particular grinding wheel employed in the centerless grindingmechanism and the operating speeds of the grinding wheel and feed wheelof the eenterless grinding mechanism are de- Pendent largely upon theparticular type of abrasive body being edged and trued. For example, inthe edging and truing of small size abrasive bodies of the typedescribed in U. 8. Patent No. 2,355,667 in which the abrasive bodyconsists of a felted fibrous abrasive-containing structure, highlysatisfactory results have been obtained by using a resinoid bonded 123grit silicon carbide grinding wheel of Nil-B4 grade, operating at aspeed of 1100 revolutions per minute with a feed wheel speed 01 130revolutions per minute. However, it is not desired to limit the presentinvention to the use of any particular type of grinding wheel or to anyparticular speed thereof, nor is it desired to limit the presentinvention to the edging and truing of any specific type of abrasivearticle since it is possible to face, true and edge rotatable abrasivebodies by the apparatus and methods herein described regardless of thetype of bond of the abrasive body.

Having described my invention in detail, it is desired to claim:

1. An apparatus adapted for use with a centerless grinding mechanism forfacing. e ing and truing rotatable abrading bodies, said apparatuscomprising, in combination, a supporting framework, a rotatable mountingplate carrying a plurality of rotatable holding means for holding theabrading bodies to be acted upon, each of said holding means beingindependently capable of axial movement. spring means for independentlyretaining each of said holding means normally out of engagement with thecenterless grinding mechanism, means for independently moving one ofsaid holding means axially toward the fiat side of the grinding wheel ofsaid grinding mechanism to dress the fiat end face of an abrading bodyheld by said holding means, means for simultaneously moving another ofsaid holding means and the abrading body being held thereby axially intoengagement by said grinding mechais acted upon by said grinding wheel toedge and true the curved surface of said body while it is rotatably heldand g surface of said grinding wheel until truing of said abrading bodyis assured whereupon said abrading body is released from its holdingmeans to pass between the grinding wheel and feed wheel of the grindingmechanism, rest means for further supporting said abrading body in thelatter part of its path of travel between the grinding wheel and thefeed wheel of the centerless grinding mechanism, means for adjusting thevertical position of the aforesaid mounting plate, means for adjustingthe lateral position of said mounting plate, mechanism for rotating saidmounting plate through a partial revolution to move the holding meanscarrying the faced abrading body into position for the aforesaid edgingand truin operation and to move another of the holding means carrying anewly inserted abrading body into position for the aforesaid facingoperation, and means for actuating said rotating mechanism.

. 2. An apparatus adapted for use with a centerd n t id truing rotatableabrading bodies, said apparatus centered radiall against theperipheralcomprising, in combination, a supporting framework,'arotatable mounting plate carrying a plurality of rotatable holdingmeansfor holding the abrading bodies to be acted upon, each of said holdingmeans being independently capable of axial movement, spring means forindependently retaining each of said holding means normally out ofengagement with the centerless grinding mechanism-means forindependently moving one of said holding means axially toward the flatside of the grinding wheel of said grinding mechanism to dress the flatend face of an abrading body held by said holding means. means forsimultaneously moving another of said holding means and the abradingbody being held thereby axially into engagement by said grindingmechanism so that said abrading body is acted upon by said grindingwheel to edge and true the curved surface of said body while it isrotatably held and centered radially against the peripheral grindingsurface of said grinding wheel until truing of said abrading body isassured whereupon said abrading body is released from its holding meansto pass between the grinding wheel and feed wheel of the grindingmechanism, rest means for further supporting said abrading body in thelatter part of its path of travel between the grinding wheel and thefeed wheel of the centerless grinding mechanism, means for adjusting thevertical position of said mounting plate, means for adlusting thelateral position of said mounting plate, mechanism for rotating saidmounting plate through a partial revolution to move the holding meanscarrying the faced abrading body into position for the aforesaid edgingand truing operation and to move another of the holding means carrying anewly inserted abrading body into position for the aforesaid facingoperation, and means for actuating said rotatable mechanism, saidplate-rotating mechanism comprising gearing means including anintermediate unidirectional or free gear which connects gear means onsaid mounting plate with gear means attached to the drive piston of anactuating cylinder mechanism, means for actuating said piston, and stopmeans for limiting the rotative action imparted by said piston toexactly the degrees of turn desired.

3. An apparatus adapted for use with a centerless grinding mechanism forfacing, edging and truing rotatable abrading bodies, said apparatuscomprising, in combination, a supporting framework, a rotatable mountingplate carrying a plurality of rotatable holding means for holding theabrading bodies to be acted upon, each of said holding means beingindependently capable of axial movement, spring means for independentlyretaining each of said holding means normally out of engagement with thecenterless grinding mechanism, means for independently moving one ofsaid holding means axially toward the flat side of the grinding wheel ofsaid grinding mechanism to face the flat end surface of an abrading bodyheld by said holding means, means for simultaneously moving another ofsaid holding means and an abrading body held thereby axially intoengagement by said grinding mechanism so that said abrading body isacted upon by said grinding wheel to edge and true the curved surface ofsaid body while it is rotatably held a d centered radially against theperipheral grinding surface of said grinding wheel until truing of saidabrading body is assured whereupon said abrading body is released fromits holding means to pass between the grinding wheel and feed wheel of10 the grinding mechanism, means for further supporting said abradingbody in the latter part of its path of travel between the grinding wheeland the feed wheel of the centerless grinding mechanism, means foradjusting the lateral position of said mounting plate, mechanism forrotating said mounting plate through a partial revolution to move theholding means carrying the faced abrading body into position for theaforesaid edging and truing operation and to move another of the holdingmeans carrying a newly inserted abrading body into position for theaforesaid facing operation, and means for actuating said rotatingmechanism.

4. Apparatus adapted for use with a center less grinding mechanism forfacing, edging and truing rotatable mounted abrading bodies, saidapparatus comprising, in combination, a supporting framework, arotatable mounting plate carrying a plurality of centering chucks, eachof said chucks being independently capable of axial movement, means forindependently retaining each of said centering chucks normally out ofengagement with the centerless grinding mechanism, means forindependently moving one of said chucks axially toward the flat side ofthe grinding wheel of said grinding mechanism to face the flat endsurface of a mounted abrading body held in said chuck, means forsimultaneously moving another of said chucks and an abrading body heldthereby axially into engagement by said grinding mechanism so that saidabrading body is acted uponby saicl' grinding wheel to edge and true thecurved surface of said body while it is rotatably held and centered insaid chuck radially against the peripheral grinding surface of saidgrinding wheel until centering of said abrading body is assuredwhereupon said abrading body is released from its chuck to pass betweenthe grinding wheel and feed wheel of the grinding mechanism, means forfurther supporting said abrading body in the latter part of its path oftravel between the grinding wheel and the coacting feed wheel of thegrinding mechanism, means for adjusting the vertical position of saidmounting plate, means for adjusting the lateral position of saidmounting plate, mechanism for rotating said mounting plate through apartial revolution to move the chuck carrying the faced abrading bodyinto position for the edging and truing operation and to move another ofthe chucks carrying a newly inserted abrading body into position forsaid facing operation, means for actuating said rotating mechanism, saidplate-rotating mechanism comprising gearing means including anintermediate unidirectional or free gear which connects gear means onsaid mounting plate with gear means attached to the drive piston of anactuating cylinder mechanism, means for actuating said piston, and stopmeans for limiting the rotative action imparted to said plate by saidpiston to the degree of turn desired.

5. An apparatus for successively facing, edging and truing rotatableabrading bodies comprising (A) a centerless grinding mechanismcomprising a grinding wheel and a coacting feed wheel together withadjusting means and operating means therefor, and (B) mechanism coactingtherewith for accurately positioning and feeding the abrading bodies tobe faced, edged and trued to said grinding mechanism, said positioningand feeding mechanism comprising a supporting framework, a rotatablemounting plate carrying a plurality of rotatable holding means for hold-11 ing the abrading bodies to be acted upon, each of said holding meansbeing independently capable of axial movement, spring means forindependently retaining each of said holding means normally out ofengagement with the centerless grinding mechanism. means for inde-'pendently moving one of said holding means axially toward the flat sideof the grinding wheel or said centerless grinding mechanism to dress theflat end face of an abrading'body held by said holding means, means forsimultaneously moving another or said holding means and an abrading bodyheld thereby axially into engagement by said grinding mechanism so thatsaid abrading body is acted upon by said grinding wheel to edge and truethe curved surface of said body while it is rotatably held and centeredradially against the peripheral grinding surface of said grinding wheeluntil truing of said abrading body is assured whereupon said abradingbody is released from its holding means to pass between the grindingwheel and feed wheel of said centerless grinding mechanism, rest meansfor further supporting said abrading body in the latter part of its pathof travel between the grinding wheel and the feed wheel of saidcenterless grinding mechanism, means for adiusting the vertical positionof said mounting plate.

, means for adjusting the lateral position of said mounting plate,mechanism-for rotating said mounting plate through a partial revolutionto move the, holding means carrying the faced abrading body intoposition for the aforesaid edging and truing operation and to moveanother of the holding means carrying a newly inserted abrading bodyinto position for the aforesaid facing operation, and means foractuating said rotating mechanism, said platerotating mechanismcomprising gearing means including an intermediate unidirectional orfree gear which connects sear means on said mounting plate with gearmeans attached to the drive piston of an actuating cylinder mechanism,means for actuating said piston, and stopmeans for limiting the rotativeaction imparted to said plate by said piston to exactly the degrees ofturn desired.

6. An apparatus for successively facing, edging and truing rotatableabradlng bodies comprising (A) a centerless grinding mechanismcomprising a grinding wheel and a coasting feed wheel together. withadjusting means and operating means therefor, and (B) mechanism coactingtherewith comprising a plurality of independently rotatable holdingmeans mounted upon a rotatable mounting plate, said holding means beingadapted for receiving and bringing a rotatable abrading body against theflat side face of the grinding wheel or said centerless grindingmechanism to face the flat end surface of said rotatable abrading bodyand simultaneously feeding a rotatable abrading body to said grindingmechanism in radially centered relationship thereto to edge and true thecurved grinding surface of said abrading body, and means for rotatingsaid mounting plate to bring each of said holding means successivelyinto positions for (1) receiving an abrasive article to be surfaced andtrued; (2) the end-facing operation; and (3) the edging and truingoperation.

7. Apparatus for edging and truing rotatable abrading bodies comprising(A) a centerless grinding mechanism comprising a grinding wheel and acoacting feed wheel together with adjusting means and operating meanstherefor, and

' aeeomi (B) mechanism for holding and positioning the abradingbody-tobedgedendtmed and for feeding said abradlng body to said grin ingmechanism, said positionin and feeding mechanism comprising a supporting a rotatable holding means forholding the abrading body to be edgedand trued. means for adjusting the vertical position of said holdingmeans, means'for adjusting the lateral position of said holding means,said holding means being capable of axial movement. means for retainingsaid holding means normally out of engagement with the aforesaidcenterless grinding mechanism, means for imparting axial movement tosaid holding means and to an abrading body held thereby to bring theabrading body into engagement with the grinding mechanism so that saidabrading body is acted upon by the grinding wheel of said mechanism toedge and true the curved surface of said body while it is rotatably heldand centered radially against the peripheral grinding surface of saidgrinding wheel until truing of said abradlng body is assured whereuponsaid abrading body is released from its holding means to pass betweenthe grinding wheel and feed wheel of the grinding mechanism to be edgedand trued thereby, and rest means for further supporting said abradingbody in the latter part of its path of travel between the grinding wheeland the coacting feed wheel of the centerless grinding mechanism.

8. Apparatus for successively facing, edging and truing rotatableabrading bodies comprising (A) a centerless grinding mechanismcomprising a grinding wheel and a coacting feed wheel together withadjusting means and operating means therefor, and (B) mechanism forholding and positioning the abrading body to be acted upon and forfeeding said abrading body to said grinding mechanism, said positioningand feeding mechanism comprising a supporting framework carrying arotatable holding means for holding the abrading article to be faced,edged and trued, said holding means and supporting framework beingpivotally mounted to permit angular movement of the holding means, meansfor adjusting the vertical position of said holding means, means foradjusting the lateralposition of said holding means whereby said holdingmeans is normally positioned to present an abrading body held thereoncentered radially in respect to the grinding wheel and feed wheel ofsaid centerless grinding mechanism, said holding means being capable ofaxial movement, means for retaining said holding means normally out ofengagement with the aforesaid centerless grinding mechanism, means forimparting angular movement to said holding means to bring said holdingmeans and an abrading body held thereby into position for facing theflat end surface of the abrading body against the flat side surface ofthe grinding wheel when'the holding means is moved axially against thegrinding wheel, means for imparting axial movement to said holdingmeans, and rest means for further supporting said abrading body in thelatter part of its travel between the grinding wheel and coacting feedwheel of the centerless grinding mechanism.

9. An apparatus adapted for use with a centerless grinding mechanism forfacing, edging and truing rotatable abrading bodies, said apparatuscomprising, in combination, a supporting framework, a rotatableperipherally geared mounting plate carrying tour rotatable holding meansfor 7 holding the abrading bodies to be surfaced and g framework carry-'trued, said holding means being radially equidistant from the center ofthe mounting plate and equally spaced one from the other thereon,

- each of said holding means being independently capable of axialmovement, spring means for independently retaining each of said holdingmeans normally out of engagement with the centerless grinding mechanism,means for independently moving one of said holding means axially towardthe fiat side of the grinding wheel of said grinding mechanism to dressthe flat end face of an abrading body held by said holding means, meansfor simultaneously moving another of said holding means and an abradinsbody held thereby axially into engagement by said grinding mechanism sothat said abradin body is edged and trued by said grinding wheel whileit is rotatably held and centered radially against the peripheralgrinding suriace of said grinding wheel until centering oi said abradinsbody is assured whereupon said abrading body is mounting plate throughone-quarter of a revolution to move the holding means carrying the facedabrading body into position for the aforesaid edging operation and tomove another 01' said holding means carrying a newly inserted abradingbody into position for the aforesaid facing operation, and means foractuating said released from its holding means to pass between thegrinding wheel and teed wheel of the grinding mechanism to be dressedthereby, means for further supporting said abrading body in the latterpart or its path oi travel between the grinding wheel and the feed wheelof the centerless grinding mechanism, means for. adjusting the lateralposition or said mounting plate for positioning each holding meansthereon in turn in centered relationship to the centerless grindingmechanism, mechanism for rotating said' rotating mechanism, saidplate-rotating mechanism comprising gearing means including anintermediate uni-directional or free gear which connects gear means onsaid mounting plate with gear means attached to the drive piston or anactuating cylinder mechanism, means for actuating said piston, said stopmeans for limiting the rotative action imparted by said piston toexactly a 90 turn.

ERIC 1?. DAHLSTROM.

REFERENCES orrnn The following references are of record in the ille orthis patent:

UNITED STATES PATENTS I Number Name Date 1,270,770 Barnes July 2, 19181,814,862 Booth July 14, 1981 2,898,887 Muller Apr. 18, 1946 FOREIGNPATENTS Number Country Date 517,824 Great Britain Feb. 9, i940 559,227Germany 861ml), 1932

